The DUP's South Down candidate in the Westminster election said he was stepping down to care for his wife Grace, who recently suffered two strokes and went through major heart surgery.

Mr Wells has been at the centre of a political storm over his stance on same-sex relationships, after he claimed children brought up by gay parents were more likely to be abused.

Then on Saturday, he sparked further uproar after it was claimed he had criticised a lesbian couple while canvassing in Rathfriland.

As well as widespread calls to resign, Mr Wells became the target of an online campaign, which he said had badly affected him and his family.

He said that he and his family had been attacked in "a deeply personal, nasty and in some cases threatening way. Some of the outbursts on social media have been particularly abusive and menacing in nature".

The pressure on Mr Wells had been increasing in recent months as he tried to juggle one of the most testing portfolios in the Stormont government - health - with the demands of looking after his wife.

Many of the health unions will be taking industrial action around the time of the May 7 election.

Early this morning, the DUP veteran told the Belfast Telegraph he had expected his wife's health would have shown greater improvement before now.

However, he said Grace will require long-term specialised care.

"As she now faces further challenges I have come to the point where I am no longer able to continue my ministerial duties and give Grace the attention she deserves," he said.

"I have been working long hours within the department by day whilst receiving a steady flow of updates from family at the hospital and then sitting at Grace's bedside throughout the night.

"Even in circumstances where Grace was sufficiently recovered and discharged, she would then more than ever require substantial assistance with rehabilitation. Having been my chief supporter throughout my career my first duty will always be to look after Grace and my family. Consequently I met with Peter and requested to stand down from ministerial office."

First Minister Peter Robinson said he respected his Health Minister's decision and thanked him for his work around the Executive table.

"I believe he has made a great contribution and always offered positive support at an Executive level," the DUP leader said.

"I would have wanted it to be otherwise but I respect Jim's decision. However, he is right to put his family first and I will fully support his decision."

Mrs Wells, who celebrated her 57th birthday in hospital with a cake and surrounded by her family, has been diagnosed with Platypnea Orthodoexia Syndrome - a condition so rare there are only 50 cases worldwide each year.

And yesterday, it was reported Mr Wells was recently diagnosed with narcolepsy, a rare disorder which can cause sufferers to fall asleep without warning. The political row started when Mr Wells linked gay relationships to child abuse at an election event in Downpatrick.

Mr Wells said a child brought up in a homosexual relationship was more likely to be abused and neglected, claiming that such marriages were less stable.